CMS results on collectivity in PbPb collisions at √sNN = 2.76 and 5.02 TeV

Abstract

Nonlinear response coeffcients of higher-order vn anisotropy harmonics for charged particles, as a function of transverse momentum (pT) and collision centrality, are measured in PbPb collisions at √sNN = 2.76 and 5.02 TeV. The nonlinear response coefficients are obtained using vn harmonics measured with respect to their own plane and the mixed harmonics. Using a fine splitting between v2{4} and v2{6} cumulants, the centrality dependence of the elliptic flow skewness is measured at 5.02 TeV PbPb collisions. The CMS also measured the v2 and v3 anisotropy harmonics of charged particles and prompt D0 mesons at |y| ≤ 1 as a function of pT and centrality in PbPb data at √sNN = 5.02 TeV collected with the CMS detector. Prompt D0 mesons, formed from the c quarks produced via initial hard scatterings, are separated up to a high extent from nonprompt D0 mesons emerged from decays of b hadrons. The results indicate that the charm quarks interact strongly with the QGP medium. Comparisons between theoretical models and data provide new constraints on the initial-state conditions and the interaction between charm quarks and the QGP medium.